This invention relates to ABA triblock copolymers wherein each A segment comprises a polyether and the B block comprises a polycarbonate.
Polycarbonates are well known, commercially available resinous materials having a variety of applications. Such polycarbonates may be prepared by reacting a dihydroxy compound, such as 2,2-bis(4-hydroxyphenyl)propane with a carbonate precursor such as phosgene, in the presence of an acid bonding agent such as sodium hydroxide. The resins are tough, rigid, have high softening temperatures, good impact strength, are usable over wide temperature limits, exhibit good dimensional stability and creep resistance. They are expensive, difficult to mold and exhibit severe environmental stress crazing and cracking.
Attempts to modify the properties of the polycarbonate resins by blending with other polymeric materials have not been met with rousing success, due in no small measure to the incompatibility of polycarbonate resins with other resinous materials.
To overcome these problems, it has been proposed to polymerize resinous materials into the polycarbonate molecule. Thus, random copolymers of polycarbonates and other polymers, such as polyethers, including random, block and graft copolymers of various polymers and polycarbonate are known. While such copolymers have met with some degree of success, there remains a need for copolymeric polycarbonates wherein the admirable properties of the polycarbonate can be retained without any significant diminution in those qualities as a result of the presence of the interpolymerized other polymer.